Copying apparatus

ABSTRACT

A copying apparatus capable of being selectively operated to feed individual cut sheets of final support material from one of a plurality of supply trays through a series of sheet processing stations to form a simplex image of an original thereon. A second mode of operation is provided wherein copy sheets fed from a first supply tray are simplexed and then automatically delivered to a second supply tray where the sheets are stored in an orientation wherein the sheets can be refed through the processing stations. The original is then changed and the imagebearing sheets fed from the second supply tray through the sheet processing apparatus to create a duplexed image on the reverse side thereof.

United States Patent [151 3,645,615 Spear, Jr. 1 Feb. 29, 1972 C PYING APPARATU Primary ExaminerSamuel S. Matthews Assistant ExaminerMonroe H. Hayes 72 l t M t l 1 men or er on R spear Jr Penfield N Y Attorney-Norman E. Schrader, James J. Ralabate and [73] Assignee: Xerox Corporation, Rochester, NY, Michael J. Colitz, Jr.

[22] Filed: July 3, 1969 [57] ABSTRACT 21 A l.N .1 83 953 1 pp 0 A copying apparatus capable of being selectively operated to feed individual cut sheets of final support material from one of Cl 271/9 a plurality of supply trays through a series of sheet processing f 8 15/00 stations to form a simplex image of an original thereon. A 0f e ond mode of operation is provided wherein copy heets fed 6 from a first supply tray are simplexed and then automatically [5 1 References c'ted delivered to a second supply tray where the sheets are stored UNITED STATES PATENTS in an orientation wherein the sheets can be refed through the processing stations. The original is then changed and the 3,273,883 1966 Balonme image-bearing sheets fed from the second supply tray through 3,348,464 10/1967 Sturoevant ..27l/9 X the sheet processing apparatus to create a duplexed image on the reverse side thereof.

9 Claims, 16 Drawing Figures 48 I I5 o U o l a'--. J

44 s l l l l 52 o o o 0 4/ 5; 34 I53 12 29 25 A 1 W O Q 53 g o H Patented Feb. 29, 1972 10 Sheets-Sheet 1 INVENTOR. MERTON R. SPEAR JR.

A TTORNEV Patented Feb. 29', 197 3,645,615

19 Sheets-Sheet 2 v mm Patented Feb. 29, 1972 3,645,615

' 10 Sheets-Sheet 4 Patented Feb. 29, 1972 3,645,615

10 Sheets-Sheet 5 Patented Feb. 29, 1972 3,645,615

16 Sheets-Sheet 6 Patented Feb. 29, 1972' 3,645,615

1 O Sheets-Sheet 7 Patented Feb. 29, 1972 3,645,615

-10 Sheets-Sheet 8 Patented Feb. 29, 1972 1O Sheets-Sheet 9 Patented Feb. 29, 1972 10 Sheets-Sheet 10 kbm WQM MUM QMN COPYING APPARATUS This invention relates in general to continuous automatic reproducing apparatus and, in particular to improved xerographic reproducing machines capable of continuously and automatically forming images on either one or both sides of sequentially fed copy sheets.

In the process of xerography, as originally disclosed by Carlson in US. Pat. No. 2,297,691, a xerographic plate comprising a layer of photoconductive insulating material affixed to a conductive backing is employed to support an electrostatic image'thereon. In the conventional method of carrying out the process, the xerographic surface is electrostatically charged unifomily over the surface and then exposed to a light pattern of the original to be reproduced to discharge the plate surface in areas where the light strikes the photoconductive layer. The uncharged areas on the surface thus form an electrostatic charge pattern in conformity with the configuration of the original. The latent electrostatic image then is developed by contacting the image areas with finely divided electrostatically attractive materials such as toner powders. The powder is held in the imaged areas by the force fields on the plate surface. Areas of greater charge concentration become areas of greater toner density while the toner in the areas of lesser charged concentration become proportionally less dense. A pattern is thereby produced in conformity with original document thereby making the' electrostatic image visible. The developed image is subsequently transferred to a final support material and suitably affixed thereto to form a permanent record of the original.

Since the disclosure of this basic concept, a variety of auto matic reproducing machines and devices have been proposed to incorporate such teachings in a manner to create copies for use on a commercial basis. For the most part, the machines in commercial utilization are limited to automatically reproducing only simplexed copies of an original. These machines are generally referred to as copiers or duplicators depending on the speed at which such copies are produced. However, in either case, these devices are incapable of producing duplexed images upon a single sheet of final support material.

It is therefore a primary object of this invention to improve automatic reproducing devices which process cut sheets of final support material.

A further object of this invention is to provide an automatic reproducing apparatus in which single sheets of final support material are forwarded to a series of sheet processing stations from one of a plurality of preselected sheet supply trays.

Yet another object of this invention is to provide apparatus wherein simplexed sheets of final support material are capable of being accumulated and restacked in a condition to be refed once again through the sheet processing stations wherein a second image is placed on a reversed side of the sheet.

These and other objects of the present invention are attained by means of a copying machine having a plurality of sheet supply trays each being capable of supporting an individual stack of cut sheets of final support material, sheet separating and forwarding means associated with the individual trays for feeding sheets seriatim from a preselected stack into an image transfer station, programmer means for selecting one of said separating and forwarding means to advance a single sheet into the transfer station, means to transport sheets forwarded into the transfer station and an image fixing station wherein a simplexed image is placed on the copy sheet and the sheet advanced to a catch tray or, in the altemative, to a second of said supply trays in which the simplexed sheets are accumulated and restacked in a condition to be refed through the sheet processing stations to place an image on the reverse side thereof.

For a better understanding of these and other objects of the present invention reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a schematic side elevation of an automatic xerographic reproducing machine for producing duplexed copies employing the apparatus of the present invention;

FIG. 2 is an enlarged partial side elevation of the sheet handling mechanism employed in the xerographic reproducing machine shown in FIG. 1 with parts broken away to better illustrate the construction thereof;

FIG. 3 is a top view showing the sheet-feeding mechanism associated with the upper supply tray illustrated in FIG. 2, and further showing the sheet separating and forwarding apparatus associated therewith;

FIG. 4 is a perspective view in partial section with pieces broken away showing the lower supply tray and its associated sheet separating and forwarding apparatus and also showing the sheet-registering apparatus employed in the automatic machine illustrated in FIG. 1;

FIG. 5 is a perspective view showing the control mechanism and linkage for conditioning the upper supply tray to receive and restack sheets when the reproducing machine illustrated in FIG. 1 is a duplex mode of operation;

FIG. 6 is a partial side elevation of the control mechanism and linkage illustrated in FIG. 5 showing crank arm mechanism in a latched condition;

FIG. 7 is a perspective view in partial section with parts broken away to clearly illustrate the sheet jogging apparatus for restacking sheets forwarded into the upper tray;

FIG. 8 is a partial front elevation in section illustrating the right-hand side jogger assembly of the paper restacking apparatus shown in FIG. 7;

FIG. 9 is a perspective view showing the comer retainers and the operating mechanism associated therewith;

FIG. 10 is a front elevation of the upper supply tray displaced horizontally from the sheet feeding position illustrated in FIG. 9 showing the right-hand corner retainer in a raised position;

FIG. 11 is an enlarged partial front elevation of the lefthand corner retainer and lifting arm shown in FIG. 9;

FIG. 12 is a right-hand side elevation of the retaining members illustrated in FIG. 11 with portions broken away showing the retainer resting in contact with the top of the sheet stack;

FIG. 13 is a side elevation of the retainer illustrated in FIG. 12 showing the lifting arm raising the retainer above the level of the stack;

FIG. 14 is a partial side view showing the cam and switching apparatus to control the movement of the upper and lower feed rolls;

FIG. 15 is a partial side view showing the crank arm mechanism illustrated in FIG. 6 in an unlatched condition;

FIG. 16 is a partial side view of the feed rolls illustrated in FIG. 9 showing the sheet sensing mechanism associated therewith.

As illustrated in FIG. 1, the apparatus of the present invention is shown herein embodied in an automatic xerographic reproducing machine capable of producing either simplexed or duplexed copies from a wide variety of originals such as copy sheets, books, or three dimensional forms. Although the present invention is particularly well suited for use in automatic xerography, the sheet feeding apparatus herein disclosed is equally well adapted for use in any number of devices in which cut sheets of material are stored in a stack and the individual sheets then separated and forwarded to a subsequent processing station. It should become apparent from the discussion below that this apparatus is not necessarily limited to its application to the particular embodiment shown herein.

The automatic xerographic apparatus illustrated in FIG. 1 includes a photosensitive plate including a photoconcluctive layer 10 that is placed over a conductive backing. The plate is formed in the shape of a drum 1 1 and the drum mounted upon a shaft 12 that is joumaled for rotation in the machine frame. Basically, the xerographic drum is rotated in the direction indicated so as to pass sequentially through a series of xerographic processing stations. The photosensitive drum and the xerographic processing apparatus are driven at predetermined speeds relative to each other from a single-drive system (not shown) and the operations thereof coordinated in order to produce proper cooperation of the various processing 5 mechanisms.

The original object to be reproduced is placed upon a transparent horizontally supported platen 14 and the original scanned by means of a moving optical scanning system to produce a flowing light image of the original. The scanning system includes an elongated horizontal extended aperture lamp l and a movable lens element 18. The lamp and lens element moves in coordination across the object supported upon the platen to focus successive incremental bans of illumination reflected from the object onto the moving drum surface at synchronous speeds therewith. The optical path is folded by means of a pair of image mirrors 19 and 20 interposed between the lens and the drum surface, the drum is first uniformly charged by means of a corona generator 13 positioned in charging station A. Under the influence of the flowing light image, the uniformly charged photoconductive surface is selectively dissipated in the nonimaged areas to form what is commonly known as a latent electrostatic image.

The latent electrostatic image is carried on the drum surface from the exposure station into the developing Station C. The developing station primarily is comprised of a developer housing 22 adapted to support a supply of two-component developer material 21 therein. The developer material is transported by means of a bucket system 23 from the bottom of the developer housing to an elevated position where the material is delivered into the active development zone. The developer material is caused to flow downwardly in contact with the upwardly moving drum surface under closely controlled conditions wherein charged toner particles are attracted from the developer mix into the image areas on the plate surface thus making the image visible.

The moving drum surface next transports the developed xerographic image to a transfer station D. Cut sheets of final support material are also moved into the transfer station, the backside of the copy sheet is sprayed with an ion discharge from a transfer corotron 25 inducing on the sheet a charge having a polarity and magnitude sufficient to attract the toner material from the drum surface to the final support material. This induced charge also electrostatically tacks the final support material to the drum surface. in order to remove the copy sheet from the drum surface, a stripper finger 28 is positioned downstream from the transfer corotron. The finer is arranged to move between the drum surface and the copy sheet and lifts the sheet from the drum surface. The stripped sheet is directed along a predetermined path of travel into contact with a stationary vacuum transport 29.

Although a preponderance of the toner material is transferred from the drum surface to the copy sheet during the transfer process, invariably some residual toner remains behind on the drum surface after transfer. This residual toner is transported on the drum surface into a cleaning station E where it is brought under the influence of cleaning corotron 30 adapted to neutralize the electrostatic charge tending to hold the residual toner to the drum surface. The neutralized toner is mechanically cleaned from the drum surface by means of a brush or the like and the toner collected within a housing 31. A conveyor moving in an endless loop through tubes 32 transport the collected residual toner back to the developer housing where it is deposited within the developer mix so that it can be once again reused in the xerographic developing process.

The copy sheet, which has been removed from the drum surface after the transfer operation, is moved along stationary transport 29 into fusing station F. The fuser 33 is basically made up of an upper fuser roll 34 and a lower fuser roll 35 mounted in operative relation to each other and arranged to coact so as to support a sheet of material in pressure driving contact therebetween. The outer surface of the lower roll is heated by means of a horizontally supported radiant heat source 38 positioned in close proximity to the roll surface adjacent to the point at which the roll contacts the image bearing support material. As the heated roll is rotated in the direction indicated, the heated surface of the lower roll is pressed into intimate contact with the image face of the support sheet.

Mechanical and heat energy transported from the roll surface to the support sheet to permanently bond the toner particles to the support material.

4 Upon leaving the fuser, the fixed copy sheet is passed through a curvilinear sheet guide system, generally referred to as 39, into cooperating advancing rolls 40 and 41. The advancing rolls forward the sheet through a linear sheet guide system 42 into a second pair of advancing rolls 43 and 44. At this point, depending on the mode of operation selected, the simplexed copy sheet is either forwarded into catch tray 51 or into upper supply tray 52 by means of a movable sheet guide 45. As will be explained in greater detail below, movable sheet guide 45, and it associated advancing rolls, are prepositioned by the machine logic system to direct the individual sheets into the desired paper tray.

It is believed that the foregoing description is sufficient for purposes of the present application to show the general operation of a xerographic reproducing machine embodying the teachings of the present invention.

Referring now specifically to FIGS. 2-16, there is shown the sheet handling apparatus of the present invention which enables a conventional xerographic machine to produce either simplexed or duplexed copies. The mechanism to accomplish this unique result includes two substantially vertically aligned supply trays 52, 53 arranged to advance copy sheets into the xerographic transfer station D and a circular sheet path adapted to operatively connect the lower supply tray 53 to the upper supply tray 52. A movable sheet guide, generally referred to as 45, is placed in the sheet path and is positionable, depending on the mode of machine operation selected, to direct xerographically processed sheets of material either into a final collecting station or into the upper supply tray 52. In the simplex mode of operation, the movable sheet guide 45 is positioned as shown by the solid lines in FIG. 1 in a position to direct copy sheets into catch tray 51.

When duplexed copies are to be produced, the movable guide is moved to the position shown in FIG. 2 and the upper tray conditioned to accept and restack simplexed copy sheets. The upper tray is further conditioned to accept and restack simplexed copy sheets. The upper tray is further conditioned to separate and forward sheets seriatim through the xerographic processing stations once again where a second image is placed on the backside of the sheet. Heretofore, the conditioning of the sheet handling equipment to accept and recirculate simplexed copy has generally been a manual operation. However, as will be explained in greater detail below, the apparatus of the present invention now makes it possible to automatically hold and then reprocess the copy sheets between copy runs.

The individual supply trays 52, 53 are movably supported between the machine frames 91, 92 upon a set of rails 104 (FIG. 2) and are capable of being moved in a horizontal direction between a first operative position and a second loading position. In the operative position, the sheet trays are supported adjacent to the sheet registering apparatus 24 wherein sheets forwarded from either tray are directed into a pair of sheet registering rolls which align the sheets prior to them being forwarded into the transfer station.

As illustrated in FIG. 2, both the upper supply tray and the lower supply tray are of similar construction. The trays include a horizontal support platform 56 having a dependent, downwardly turned, vertical aligned front flange 54, a stationary side margin guide 59 and a movable side margin guide 58. The stationary margin guide is rigidly affixed to the support platform and has a vertically extended leg thereon. The movable guide similarly has a vertically leg complimentary to that of the stationary side margin guide and is adapted to cooperate therewith to guide individual sheets forwarded from the trays along a predetermined path of travel into the sheet registering apparatus 24. The movable side margin guide is slidably carried upon the support platform and arranged to move laterally thereon making it possible to accommodate sheets of varying lengths upon the platform. To aid in the correct positioning of a stack of final support sheets within the tray, the tray is provided with an indexing scale 55 for laterally positioning the movable side margin guide.

An L-shaped rear retaining member 64 is affixed to each of the vertical legs of the side margin guides. The two rear retaining members associated with each supply tray cooperate to longitudinally position the stack upon the support platform. The members are basically formed of an angular plate including a rear wall 60 and a flange 61 adapted to overlay in parallel relation the vertical legs of the side margin guide members. Each of the side margin guides is provided with a stud, (not shown) which protrudes through a horizontally slotted hole in the flange 61 of the rear retaining member 64 and is engaged by a thumb nut 62 whereby each rear retaining member may be adjusted and tightened against the side margin guide.

To feed sheets of final support material one at a time from each of the individual supply trays, there is provided a sheet separating and feeding means, generally referenced 85, consisting of a pair of driven feed rollers 86 supported in a self aligning manner within floating bearings secured to a shaft 87. The shaft 87, in turn, is secured in bearing blocks 90 mounted in the front or free ends of two support arms 88. The opposite ends of the support arms are similarly secured to a drive shaft 89 and the drive shaft journaled for rotation in the machine frames 91, 92 above and to the rear of the individual supply trays permitting the feed rollers to rest freely in contact with the uppermost sheet in the stack.

As individual sheets are fed from the stacks, the freely mounted, self-adjusting, feed rolls drop down into contact with the next subsequent sheet in the stack. Each feed roller is operatively connected to the drive shaft 89 by means of a clutch and pulley arrangement. The prescribed sheet-feeding motion is translated to the rollers through the clutch and pulley arrangement in proper timed relation with an image on the drum surface wherein the advanced sheets and the image arrive at the transfer station at the same time.

The upper supply tray 52 and the lower supply tray 53 are provided with similar electromagnetic clutches CL-l and CL- 2, respectively. The clutches include a drive unit 96 pinned to the drive shaft 89 and a driven unit 95 which is rotatably supported upon the drive shaft in a roller bearing provided (not shown). A timing pulley 83 is locked to the driven end of the clutch and is operatively connected to a second drive pulley 93, which is pinned to shaft 87, by means of a timing belt 82.

To facilitate movement of either of the supply trays in a horizontal direction between their respective operative positions and loading positions, there is provided elevating means to raise the feed rollers above the top level of the trays. As shown, a camming arm 116, having an offset 117 thereon, is rotatably supported between the machine frames 91 and 92. The offset 117 is arranged to pass through an elongated aperture 118 in both the support arms 88 of the feed roll assemblies. One end of the camming arm passes through the machine frame 91 and has a crank arm 119 secured thereto. Rotation of a crank in a clockwise direction as shown in FIG. 3 causes the offset 117 to move upwardly raising the feed roller support arms and thus elevating the entire feed roller assembly to a level sufficient to allow the supply tray to be operatively repositioned in a horizontal direction.

As can be seen, the side of each of the support platforms adjacent to the sheet registering apparatus is unobstructed so that an uninterrupted path of travel is provided along which individual sheets of support material, which have been separated from the individual stacks, can be forwarded into the registering means. To retain the front margins of the individual stacks in alignment during sheet separation and forwarding there is provided a pair of front margin sheet retaining members 70. Each retaining member 70 includes a main body 74 about which is rotatably mounted a hinged tab 75. As illustrated in FIGS. -13, the tab is pivotally mounted in the body upon a pivot rod 79. A torsion spring 81 is wound about the rod and normally biases the tab against a stop 80 affixed to the body of the member to hold the tab in a horizontally extended position substantially perpendicular to the body of the retainer. I

As shown in FIG. 10, each of the two retaining members associated with the individual trays is carried within the free end of a lifting arm 72 with the opposite end of the lifting arm rotatably supported below the level of the support platform upon a pivot pin 73 affixed to plan 54. The lifting arms are arranged to swing the retaining members through a vertical plane substantially parallel to the front margin of the individual stacks. A second set of actuator arms is also rotatably supported below the level of the platfonn in flange 54. The actuator arms are supported upon pivots 124 so that the arms, in a free or natural position, rest in contact with stops 124 as illustrated in FIG. 10. Each actuator arm has a substantially horizontal dependent flange at the opposite end thereof adapted to operatively engage a pin affixed to lifting arm 72.

In operation, when fresh sheets are added to the trays, the trays are moved to a loading position and fresh sheets of support material simply aligned in the tray against the side and rear guides directly on top of the front edge retaining members. When the tray is moved from the loading position toward the operative position in the direction indicated in FIG. 10, the retaining members will be automatically positioned in operative engagement with the topmost sheet in the stack in the position illustrated in FIG. 12.

A camming member 128 (FIG. 10) is supported in a housing 129 and the housing affixed to frame 91. The camming member is supported in a position wherein the camming member engages the bottom surface 130 of the actuator arms 122 as the tray is moved between positions. The camming member is freely supported so as to swing downwardly in a clockwise direction from its normal home position when the tray is moved to the loading position. However, the member is incapable of swinging in the opposite direction and therefore engages surface 130 when the tray is returned to the operative position as indicated in FIG. 10. The bottom surface of the actuator arms are cam profiles which impart a prescribed motion to the lifting arms causing the lifting arms to first elevate the retaining members 70 above the level of the stack and then return the members in a downward direction. The prescribed motion is translated from the actuator arms to the lifting arms through means of flange 121 swinging upwardly into contact with pin 120.

Each retaining member 70 is journaled for rotation in the free end of the associated lifting arm 72 upon a pin 71. The retaining members 70 are designed so that their respective centers of gravity are located at a point wherein the freely supported member normally assumes a position with the tab nor mally extended in a horizontal position as shown in FIG. 11. When new sheets are added to the supply stack the sheets rest on top of tabs 78. The fresh sheets therefore impede the upward movement of the tab when the lifting arms are elevated causing the hinged tabs to swing downwardly about the upwardly moving body 74. The tabs continue to swing downwardly until they are removed from beneath the stack as shown in FIG. 13. Further elevation of the lifting arms moves the tabs upwardly in contact with the front margin of the stack until such time as the top of the stack is cleared. At this time, the biasing spring acting in conjunction with the downwardly pulling weighted end 75 of the tab, forces the tab to move rapidly back into its normal horizontally extended position. As the lifting arms start downwardly through the prescribed path of motion, the extended tabs engage the top sheet on the stack as shown in FIG. 12. The actuator arms are allowed to continue to swing down until the come to rest once again against stops 124 so that the retaining members, and their associated lifting arms, hang in a suspended manner upon the stack to support the stack in sheet feeding alignment.

In order to feed individual sheets from either of the two supply stacks, the topmost sheet in the stack is first separated from the main body of the stack by forming a separating buckle in the sheet and the sheet then forwarded to subsequent sheet handling means within sheet registering apparatus 24. At the beginning of each sheet feeding cycle, the feed rollers 86 are rotated in a direction to cause the leading edge of the topmost sheet in the stack to be moved rearwardly from beneath the front edge retaining members 70. The trailing edge of the sheet, however, is held stationary by the rear walls 60 in rear retaining members 64 so that a separating buckle is formed longitudinally across the sheet. The suspended front retaining members 70, and their respective lifting arms, at this time drop down into supporting engagement with the main body of the stack. The direction of rotation of the feed rollers is then reversed and the now separated sheet driven over the top of the horizontally extended tabs 75 into sheet registering apparatus 24. The rear surfaces of the extended tabs taper down in knife edge fashion so as to allow the forwarded sheets to pass easily thereover.

Drive shafts 89, associated with the two feed roller assemblies 85, are driven from a main programmer shaft 101 rotatably supported in the sheet registering apparatus 24 (FIG. 3). The programmer shaft is, in turn, driven in timed relation with the xerographic drum by means of the main machine drive (not shown) to coordinate sheet advancement with the processing of an image on the drum surface wherein the image and the copy sheet move into transfer station D in synchronous timed relation.

A pair of sheet feeding control cams 105, 106 are locked to the programmer shaft and operate through their associated cam follower linkage mechanisms to turn drive shafts 89 to separating and forwarding sheet from the trays into the sheetregistering apparatus. As can be seen, the sheets forwarded from the upper tray into the register stop rolls 138, 139 move along a path of travel considerably longer than that followed by sheets forwarded from the lower tray. Consequently, in order that sheets supplied from the upper tray reach the transfer station at the same time as the image on the drum surface, the upper tray separating and forwarding operations must be initiated prior in time than those of the lower tray during any given copying cycle. The upper tray control cam 106, therefore, is advanced in relation to the lower tray control cam, upon the programmer shaft in the direction of rotation, a distance corresponding functionally to this difference in sheet travel time.

As illustrated in FIGS. 2 and 4, the upper feed roller control cam 106 translates the prescribed sheet feeding motion to the upper tray drive shaft by means of cam follower arm 111 and link 113 acting through segmented gear 114 and pinion 115. Similarly, identical motion is translated, later in time, to the lower tray drive shaft from the lower feed roll control 105 by means of cam follower 107 and link 109 acting through segmented gear 110 and pinion 108.

For each complete revolution of the programmer shaft, a prescribed motion is translated to the upper and the lower feed roller drive shafts 89 through their respective control cam systems which turns the drive shaft first in one direction for one half a cycle and then in the opposite direction for the second half of the cycle. The drive shafts are locked to the main drive system and continually turned in timed relation with the drum surface when the machine is in operation. Through means of a clutching arrangement, only a portion of the shafts total motion, however, is imparted to the feed rollers during each paper forwarding cycle.

In practice, the desired mode of operation is that selected causing a signal to be sent to the machine control logic 139 (FIG. 14). The signal is passed to the appropriate gate and either one of the two trays readied to feed sheets. However, before the signal is passed to the preselected tray clutch, an enabling signal must be received by the gate from a clutch timing switch. The energization of the individual clutches CL-l or CL-2, associated with the upper and lower trays, is controlled by means of a pair of limit switches SW-l and SW-2, respectively, which are actuated by timing cam segments 134 and 135 secured to the drum shaft 12. The timing cam segments are arranged to hold the selected clutch energized for a period during each sheet feeding cycle wherein the feed rollers perform the heretofore described separating and forwarding functions. The appropriate clutch is energized as the feed roll drive shaft approaches the midpoint of its prescribed motion, that is, the point at which the direction of shaft rotation is reversed. The timing is such as to cause the feed rollers to pull the uppermost sheet on the stack from beneath the retaining members 70 but insufficient to push the sheet from beneath the feed rollers thus fonning a separating buckle in the sheet. The clutch is held energized through the midpoint of the cycle. As the direction of feed roller rotation is reversed the separated sheet is forwarded by the rollers into subsequent sheet advancing means associated with the sheet registering apparatus. At this time, the limit switch contact is broken and the clutch deenergized. The feed rollers are idled and allow the trailing edge of the sheet to be pulled from thereunder by the subsequent sheet advancing means. The clutch remains idle until such time as another sheet feeding cycle is initiated.

Referring now specifically to FIGS. 2 and 4, there is illustrated a sheet registering apparatus 24 including two pairs of register stop rolls 138 and 139 arranged to momentarily interrupt the advancement of individual sheets fed from either the top tray or the lower tray. The upper roll 138 has a stop face therein adapted to project downwardly into the sheet path of travel and interrupt the leading edge of a sheet moving therealong. The sheet is driven into the two stop faces for a period of time sufficient to insure proper registration and then lower pinch rolls 139 are cammed into friction driving contact with rolls 138 and the registered sheet rapidly accelerated to machine speed. Upon reaching machine speed, a second pair of drive rolls 160 (FIG. 4) and their associated pinch rolls (not shown) take over the advancing function and deliver the sheet into transfer station D.

Here again the movement of the individual sheets is controlled by a series of cams secured to the programmer shaft 101. The motion of the register stop roll 138 is controlled by cam 143 (FIG. 4) which turns a drive shaft 148 through means of a cam follower 145 and a segmented gear 146 acting on pinion 147. Shaft 148 is journaled in the side frames of the sheet registering apparatus in parallel relation to the stop roll support shaft 149 and has a pair of drive pinions 150 secured thereto. Each of the stop rolls 138 is mounted for free rotation upon shaft 149 and has a dependent gear 151 thereon which meshes with the drive pinion 150.

In operation, cam 143 positions the stop face in a condition to interrupt and register a sheet being guided towards the transfer station. After registration, pinch roll 139 is cammed upwardly towards the stop roll 138 to exert a driving pressure upon the sheet. As shown in FIGS. 1 and 2, the camming of the pinch roll is controlled by a second cam 153 acting through follower arm 154 and link 155 secured to rocker shaft 162. The stop rolls 138 accelerate the sheet to the desired velocity in less than one complete rotation of the roll. When machine velocity is reached, the advancing function is then taken over by a set of drive rolls secured to constantly turning shaft 148 and the stop rolls idled. A second set of pinch rolls are cammed to drive the moving sheet into pressure contact with the drive rolls by means of a earn 156 (FIG. 1) acting through cam follower 157 and link 158 secured to a second rocker shaft 163. When the trailing edge of the sheet has cleared the stop rolls, the stop rolls are once again placed in as condition to intercept the next subsequent sheet being guided into the transfer station.

While sheets fed from the lower tray are advanced directly into the register stop rolls, the sheet fed from the upper tray being at a more remote location must be delivered first into a constantly moving set of supplementary drive rolls 140 and 141 which further advance the sheet along the guided path of travel shown in FIG. 2 into the registration station.

To duplex, the operator first insures that the upper tray is emptied of all copy sheets, a first original is placed upon the copyboard prior to the duplex mode of operation selected. Selection of the duplex mode of operation causes a solenoid SOL-l (FIG. 5, 6) to be energized pulling down link 210. The downward motion of the link causes the lever arm to be rotated about stud 199 forcing flexible member 203 into biasing contact with a crank arm 204. The crank arm 204 is provided with an arcuate-shaped elongated hole 205 having a notch (not shown) machined in the bottom wall thereof. A dependent arm 207 on the cam follower carried a drive pin 206 which is arranged to pass through the elongated slotted hole provided in the crank arm. Normally the pin will rise freely along the top surface of the slotted hole 205 wherein the crank arm remains relatively stationary as the follower arm is rocked by the continually rotating cam 213. However, as flexible member 203 is forced upwardly by the energized solenoid SOL-1, pin 206 is forced to ride along the bottom surface of the slotted hole. Pin 206 falls into the notch provided in the lower surface of the slotted hole and is held therein by the pressure exerted by flexible arm 203. Further motion of the cam is then translated directly to the crank arm through the follower arm 208, which is biased in a continuous contact with the cam face by spring 198, causing the crank to reciprocate back and forth in substantially a horizontal direction.

During the first reciprocating cycle of the crank arm, downwardly extended dependent projection 217 formed in the opposite end of the crank arm moves into engagement with a stub pin 218 securely staked to movable plate 220. The movable plate is pivotally mounted in machine frame 92 upon pivot pin 221. As the crank arm, as shown in FIG. 6, is driven forward, that is, to the right, toward a fully extended position, the movable plate is rotated in a clockwise direction. During this period, solenoid SOL-1 is continually held energized and continues to exert a downward pressure on the lever arm 202. As illustrated in FIG. 15, the arm, however, is initially prevented from swinging to a full down position by a stop pin 222 affixed in the lower portion of plate 220. Further movement of the crank arm, however, forces the stop pin 222 to be moved out of interference with the extended portion 196 of lever arm 202 allowing the solenoid to pull the lever arm to a full down position. Now, as the crank arm starts back from is fully extended position, the stop pin 222 moves into contact with the vertical surface 223 on the extended arrn 196 to latch movable plate 220 in a stationary position as illustrated in FIG. 6. The plate will remain in this latched position as long as solenoid SOL-l is held energized.

This initial rotation of plate 220 to a latch position conditions the upper tray to accept and restack sheets supplied from the lower tray which have been xerographically processed to produce an image on one side thereof. First, movable guide 45 (FIG. 2), positioned in the circular sheet path, is pulled downwardly to direct sheets fed along the sheet path directly into the upper tray. Secondly, the upper supply tray feed rollers are elevated out of the sheet feed path to permit sheets to be expelled from the movable guide directly into an upper tray in an unobstructed manner. The movable guide 45 is pivotally mounted about a shaft 50 (FIG. 2) and normally held in an up position by spring 192. The movable guide is driven from the normally up position to a down position by means of actuator link 228. One end of the link is freely supported in the rnovable guide 45 upon shaft 187 (FIG. 5) while the opposite end of the link is mounted upon stop pin 222 which is staked in rotatable plate 220. Pin 222 extends rearwardly through a hole provided in machine frame 92 and is slidably received within a slotted hole 227 in the actuator link. An adjustment screw 229, which is mounted in a vertical flange 230 on the driven end of the link, limits the length of the path of travel along which pin 222 may slide within hole 227. As the plate 220 is moved in a clockwise direction as explained above, stop pin 222 engages adjustment screw 227 pulling the link 228 towards the rear of the upper tray. This rearward motion of the link, in turn, pulls the movable guide to a full down position so that it is now in a condition to feed sheets directly into tray 53.

As illustrated in FIG. 2, upper sheet guide 194 of the sheet registering apparatus is provided with a hinge 195 and is normally held in an up position by means of a spring 192. As the movable guide member 45 moves down into the duplexing position, extended section 191 on the guide contacts the top of the hinged guide member moving the guide out of the way so that the transport feed rolls 48 and 49 can be placed in a position to advance sheets from the movable transport into the upper tray.

When plate 222 is moved to the latched position by solenoid SOL-l further mechanism is activated to elevate the upper tray feed roller assembly. As seen in FIG. 5 camming rod 116 passes through machine frame 92 and the extended end thereof secured in eccentric link 240. The extreme end of the eccentric link is joumaled in the top portion of a second S- shaped link 241 and the opposite end of the S-shaped link journaled for rotation in movable plate 220 upon the pin provided. As the crank arm is driven through its first reciprocating cycle, latching plate 220 is held in a latched condition against pin 222 and the S-shaped link 241 is pulled to a down position. This downward motion of the link causes camming rod 116 to be rotated in a direction raising offset 117 to an elevated position thus forcing the feed roller assembly above the top level of the upper tray. Therefore, during the first full reciprocating cycle of the crank arm 204, the movable guide 45 is moved to a down position and the upper feed rolls are elevated to allow sheets forwarded along the circular path of travel to be fed into the upper tray.

Sheets forwarded from the lower tray are registered in the register stop rolls and then passed through transfer station D to the xerographic processing stations where a first image is placed upon the copy sheet. The copy sheet advanced by means of the heretofore described sheet advancing rolls into the upper supply tray. Delivering a simplex sheet to the upper tray, however, is not in itself sufficient to insure that the sheets will be properly stacked and aligned prior to the start of the duplexing operations. It has long been known that improperly stacked sheets are the cause of misregistration and misfeeding of sheets resulting in the paper jams and in extreme cases of machine breakage. The upper tray therefore is provided with means to receive and restack the simplexed sheets delivered from the lower supply tray.

The sheet restacking apparatus associated with the upper supply tray 52 is shown in greater detail in FIGS. 7 and 8. The restacking fundamentally consists of two front margin aligning members or joggers 245 and two side margin joggers generally referred to as 257, both of which are driven by means of crank arm 204. When a simplexed sheet has been delivered into the upper supply tray, the front joggers are moved upwardly into contact with the front margin of the sheet forcing the sheet into registration with the backwall 60 of the supply tray. Simultaneously, two side joggers move into contact with the side margin of the sheet to laterally align the sheet within the tray.

The front joggers 245 are secured to a shaft 248 and the shaft rotatably supported in the machine frame (not shown) below the level and a bit forward of the open end of the upper supply tray 52. The shaft is coupled to the crank arm 204 by means of an extension spring 251 pinned to the crank arm. Extension of the crank arm during any reciprocating cycle causes the spring to pull a coupling 250 in a clockwise direction rotating shaft 248 in a counterclockwise direction. The front joggers are thus raised from a near horizontal position below the level of the tray to a sheet engaging vertical position as shown in FIG. 7 to force the sheets rearwardly into registration against the backwall 60 of the tray. In order to insure that each sheet is registered against the back of the tray, the front joggers are permitted to be moved by the crank arm a greater distance than required to move the sheet into contact with the rear wall 60. As can be seen, however, the pressure imparted by the cam system is regulated by the dampening action of the spring so that the spring is deformed before any damaging I upon shaft 258 and which extends horizontally beneath the upper supply tray 52. As shown in FIG. 7, the left-hand end of the bail shaft is affixed to a link 256 and the link rotatably secured in the crank arm 206 wherein the bail swings upwardly as the crank moves to its fully extended position. Riding in contact with the top surface of the bail are two vertically extended rods 259 slidably supported within individual housings 260. The housings are mounted adjacent to the side margin guides in the cut outs provided upon the supply tray platfonn 56. The vertically extended rod is arranged to pass through both the housing and the support platform and rides freely in contact with the bail carried beneath the tray platform.

FIG. 8 illustrates the internal arrangement of the rod within the individual housings 260. The rod is supported within the housing frame and has an inverted truncated member 261 affixed to the center portion thereof. A compression spring 262 is secured between the top of the housing and on the truncated member and acts to hold the vertical rod in biasing contact with the bail 255. A flexible bar 263 is locked at one end to the housing by means of a clamp 264 (FIG. 7) and carries a vertically extended side margin jogger 246 on the free end thereof. The flexible bar rides in contact with the truncated member and is flexed inwardly towards the side margin of the upper supply stack as the rod is raised by the bail. The two side joggers are adapted to move in concert into contact with the sheets to position the sheets therebetween in proper sheet feeding alignment. Here again, the restacking force is transmitted through a flexible member which prevents sheet damaging forces from being imparted from the drive mechanism to the copy sheets.

In practice, the programmer shaft moves through one complete revolution for each xerographic processing cycle and each sheet feeding cycle. The crank is also controlled by the programmer shaft motion so that one reciprocating cycle of the crank is produced for each rotation of the programmer shaft. Because the motion of the individual joggers is physically linked to the crank arm the joggers will act to align each individual sheet fed 'into the upper tray during duplexing operations thus insuring that the resultant stack is properly maintained in a condition wherein sheets are able to be once again fed through the xerographic processing stations.

When the upper tray is cleared prior to duplexing the retaining members are automatically repositioned in the bottom of the upper tray. The simplexed sheets delivered into the tray are simply restacked directly above the extended tabs.

Upon completion of the restacking operation, cam 213 is permitted by the machine logic to make at least one more complete revolution. As the cam follower passes the low point in its motion, a second solenoid SOL-2 is energized pulling the floating arm 271 (FIG. 9) inwardly towards the solenoid body. A universal member 272, passing through the floating arm, is rotatably mounted in a fixed position on vertical shaft 273. As can be seen, when the solenoid is energized the universal member is pulled in a counterclockwise direction towards the solenoid. One end of the follower arm 208 is provided with a flange 274 which is moved downwardly as the follower traces the low side of the cam profile. When the flange is in the low position, the universal member 271 is able to be pulled over the flange by the solenoid. As the follower starts back in an upward direction during a subsequent rise portion of the cam cycle, the flange is brought into contact with the bottom of the universal member. Further upper movements of the flange causes the universal to push against a fixed bushing 275 secured to shaft 273 lifting the shaft.

The bottom of the vertical shaft 273 is pinned to a link 278 which, in turn, is pivoted about a stub shaft 279. The stub shaft is held in a stationary position in mounted block 280 which is secured to the machine frame. The other end, or top of the vertical shaft 273 is pinned to an actuator arm 283 and the arm rockably supported by stub shaft 284 secured in mounting block 285. As the shaft is raised, actuator arm 283 is swung in a clockwise direction as shown in FIG. 9 forcing a dowel pin 288 secured thereto into contact with a horizontal slide member 290 slidably supported in the upper tray.

Slide member is slidably mounted in the downwardly turned front flange 56 of the upper tray platform below the level of the stack and is adapted to reciprocate in a horizontal direction. When the tray is in an operative position, the slide 290 is biased into contact with dowel 288 secured in arm 283 by means of an extension spring 307. A pin 309 is staked to the upper tray platform flange and passes through a slotted hole 308 provided in the slide. A second pin 310 is similarly staked to the slide member and the extension spring supported therebetween in a working position so as to urge the slide member against dowel 288.

As previously described two actuator arms 122 are supported in the front of the upper tray and normally rest against stops 124 affixed to slide member 290. As can be seen, as shaft 273 moves upwardly, dowel pin 288 is forced against slide 290 causing the slide to move in a horizontal direction against the biasing force of spring 307. As the slide moves in the horizontal direction, stops 124 are moved over the cam surfaces 316 of the actuator arms 122 causing the arms to swing in a clockwise direction. Slide 290 is moved far enough in a horizontal direction to displace pin 124 sufficiently to cause the lifting arms to raise retaining members 70 as described above to an elevation above the top level of the tray. As the cam 213 passes the rise portion of the cycle and returns toward the low portion thereof, the slide returns to its home position. At this time, the retaining members carried by the lifting arms are brought into engagement with the top of the stack proprietary to sheet feeding operations. A manual slide actuator 315 is provided at the opposite side of each tray which is affixed to the slide. If for some reason the retainer fails to engage the stack properly, the operator simply pulls the actuator laterally to recycle the retainers into proper alignment.

At the completion of the automatic restacking and retainer positioning operation, both solenoids SOL-l and SOL-2 are deenergized. Deenergization of solenoid SOL-1 allows pin 206 to once again ride in contact with the top surface of slotted hole 205 in the crank arm. At this time arm 202 is moved upwardly unlatching movable plate 220 and the plate allowed to return once again to its normal home position thus placing the upper feed'roll assembly in contact with the top of the stack and returning the movable sheet guides to the up position wherein sheets are capable of being fed from the upper tray through the circular paper feed directly into catch tray 51 (FIG. 1 At this time, the operator places a second original on the copyboard and starts the upper tray sheet feed operations.

The simplex sheets are passed through the registration system and the xerographic processing stations wherein a duplexed image is placed on the backside thereof and the duplexed copy exhausted exterior the machine in catch tray 51.

A limit switch LS-3 is carried on one of the upper tray feed roll support members 88 and has a sensing arm 310 thereon capable of riding in contact with the top of the stack. When the last simplexed sheet is fed from the upper tray the actuator arm 312 is allowed to fall through opening 311 in the upper tray platform sending a signal to the logic system that the duplexing operations are completed. This signal is then used to program the mechanical drive system to tenninate the machine operations.

While this invention has been disclosed with references to the structure described herein, it is not to be confined to the details as set forth, and this application is to cover all modifications and changes which may come with the scope of the following claims:

What is claimed is:

1. A copying apparatus of the type wherein an image of an original is developed on a moving image retaining member and the image transferred to a cut sheet of final support material including a plurality of supply trays for supporting individual stacks of cut sheets of final support material,

sheet separating and forwarding means operatively associated with each of said supply trays for separating individual sheets from a stack and advancing the sheet to an image transfer station,

drive means operatively associated with each of said separating and forwarding means, said drive means being arranged to move in predetermined timed relation with said moving member,

a normally decoupled clutch means interposed between sad drive means and each of said sheet separating and forwarding means for coupling and decoupling said drive means from said separating and forwarding means,

programmer means to couple one of said clutches to said drive means for a period of time wherein a single sheet of final support material is forwarded from a preselected stack into the transfer station in timed relation with an image on the moving member wherein the image is transferred from said member to said copy sheet.

2. The apparatus of claim 1 wherein said clutch means comprises an electromagnetic clutch actuated by a switching means operatively associated with said programmer means.

3. The apparatus of claim 2 wherein said drive means includes a shaft,

means to rotate said shaft at a predetermined rate in relation to the moving image retaining member,

a plurality of cam members equal to the number of support trays and being secured to said shaft, said cam members being operatively connected to each of said separating and forwarding means and arranged to translate a motion to each of said separating and forwarding means whereby a sheet forwarded from any of said plurality of trays moves into the transfer station in synchronous timed relation with the image on the moving member.

4. The apparatus of claim 1 further including sheet registering means positioned adjacent to the transfer station and being arranged to register individual sheets prior to the sheets being advanced into the transfer station.

5. in a coping apparatus of the type wherein a latent image of an original is formulated and developed on a moving image retaining member and the developed image transferred to a cut sheet of final support material, the apparatus having a sheet transport means to move individual cut sheets of final support material along a predetermined path of travel through a series of sheet processing stations including a transfer station wherein the individual cut sheets are moved into-contact with the image retaining member in synchronous relation with a developed image thereon and the image transferred from the surface to the cut sheet and an image fixing station wherein the image is affixed to the cut sheets, the improvement comprising a series of vertically aligned sheet supply trays for supporting individual stacks of cut sheets of final support material in substantially a horizontal position including an upper supply tray and a lower supply tray each having individual sheet separating and forwarding means associated therewith for separating the uppermost sheet in a stack and forwarding the sheet to the sheet transport means,

drive means operatively related to each of said separating and forwarding means and being arranged to move in predetermined timed relation with the moving image retaining member,

a normally decoupled clutch means interposed between said drive means and each of said sheet separating and forwarding means for coupling and decoupling said drive means from said forwarding and separating means,

programmer means to couple one of said clutches to said drive means for a period wherein a single sheet of final support material is forwarded from a preselected stack to the sheet transport means in timed relation with an image on the moving image retaining member,

sheet conveyor means positioned between the final sheet process in station and a sheet receiving station for conveying in ividual sheets therebetween and having means associated therewith movable to a position wherein a first imaged sheet leaving the final processing station is, in the alternative, directed into said upper supply tray,

control means to condition the apparatus to store first imaged sheets of final support material in an orientation to be refed through the sheet processing stations including switching means to condition said programmer means to feed sheets of support material from said lower tray through the sheet processing stations, means to selectively position said sheet conveyor means in a position wherein first imaged sheets leaving the sheet processing stations are forwarded into the upper tray, and means to condition the upper tray to receive and restack sheets forwarded therein in a position to be refed once again through the sheet processing stations wherein a second image is placed on the side of the sheet opposite the side receiving said first image.

6. The apparatus of claim 5 wherein said means to separate and forward individual sheets from the stacks includes a pair of feed rolls being arranged to ride in friction driving contact with the uppermost sheet in the individual stacks.

7. The apparatus of claim 6 wherein said means to condition the upper tray includes elevating means to raise said feed rolls above the height of the stack wherein the first imaged sheets forwarded into said upper supply tray.

8. The apparatus of claim 7 further including means operable upon the restacking of the first imaged sheets to condition said apparatus to feed said first imaged sheets through the sheet processing stations and deliver said sheets to the sheet receiving station.

9. The apparatus of claim 5 further including sheet registering means positioned adjacent to the sheet transfer station to register sheets being transported by said sheet transport means prior to their delivery to said sheet transfer station. 

1. A copying apparatus of the type wherein an image of an original is developed on a moving image retaining member and the image transferred to a cut sheet of final support material including a plurality of supply trays for supporting individual stacks of cut sheets of final support material, sheet separating and forwarding means operatively associated with each of said supply trays for separating individual sheets from a stack and advancing the sheet to an image transfer station, drive means operatively associated with each of said separating and forwarding means, said drive means being arranged to move in predetermined timed relation with said moving member, a normally decoupled clutch means interposed between sad drive means and each of said sheet separating and forwarding means for coupling and decoupling said drive means from said separating and forwarding means, programmer means to couple one of said clutches to said drive means for a period of time wherein a single sheet of final support material is forwarded from a preselected stack into the transfer station in timed relation with an image on the moving member wherein the image is transferred from said member to said copy sheet.
 2. The apparatus of claim 1 wherein said clutch means comprises an electromagnetic clutch actuated by a switching means operatively associated with said programmer means.
 3. The apparatus of claim 2 wherein said drive means includes a shaft, means to rotate said shaft at a predetermined rate in relation to the moving image retaining member, a plurality of cam members equal to the number of support trays and being secured to said shaft, said cam members being operatively connected to each of said separating and forwarding means and arranged to translate a motion to each of said separating and forwarding means whereby a sheet forwarded from any of said plurality of trays moves into the transfer station in synchronous timed relation with the image on the moving member.
 4. The apparatus of claim 1 further including sheet registering means positioned adjacent to the transfer station and being arranged to register individual sheets prior to the sheets being advanced into the transfer station.
 5. In a coping apparatus of the type wherein a latent image of an original is formulated and developed on a moving image retaining member and the developed image transferred to a cut sheet of final support material, the apparatus having a sheet transport means to move individual cut sheets of final support material along a predetermined path of travel through a series of sheet processing stations including a transfer station wherein the individual cut sheets are moved into contact with the image retaining member in synchronous relation with a developed image thereon and the image transferred from the surface to the cut sheet and an image fixing station wherein the image is affixed to the cut sheets, the improvement comprising a series of vertically aligned sheet supply trays for supporting individual stacks of cut sheets of final support material in substantially a horizontal position including an upper supply tray and a lower supply tray each having individual sheet separating and forwarding means associated therewith for separating the uppermost sheet in a stack and forwarding the sheet to the sheet transport means, drive means operatively related to each of said separating and forwarding means and being arranged to move in predetermined timed relation with the moving image retaining member, a normally decoupled clutch means interposed between said drive means and each of said sheet separating and forwarding means for coupling and decoupling said drive means from said forwarding and separating means, programmer means to couple one of said clutches to said drive means for a period wherein a single sheet of final support material is forwarded from a preselected stack to the sheet transport means in timed relation with an image on the moving image retaining member, sheet conveyor means positioned between the final sheet processing station and a sheet receiving station for conveying individual sheets therebetween and having means associated therewith movable to a position wherein a first imaged sheet leaving the final processing station is, in the alternative, directed into said upper supply tray, control means to condition the apparatus to store first imaged sheets of final support material in an orientation to be refed through the sheet processing stations including switching means to condition said programmer means to feed sheets of support material from said lower tray through the sheet processing stations, means to selectively position said sheet conveyor means in a position wherein first imaged sheets leaving the sheet processing stations are forwarded into the upper tray, and means to condition the upper tray to receive and restack sheets forwarded therein in a position to be refed once again through the sheet processing stations wherein a second image is placed on the side of the sheet opposite the side receiving said first image.
 6. The apparatus of claim 5 wherein said means to separate and forward individual sheets from the stacks includes a pair of feed rolls being arranged to ride in friction driving contact with the uppermost sheet in the individual stacks.
 7. The apparatus of claim 6 wherein said means to condition the upper tray includes elevating means to raise said feed rolls above the height of the stack wherein the first imaged sheets forwarded into said upper supply tray.
 8. The apparatus of claim 7 further including means operable upon the restacking of the first imaged sheets to condition said apparatus to feed said first imaged sheets through the sheet processing stations and deliver said sheets to the sheet receiving station.
 9. The apparatus of claim 5 further including sheet registering means positioned adjacent to the sheet transfer station to register sheets being transported by said sheet transport means prior to their delivery to said sheet transfer station. 